Fluid couplings comprising interconnectable coupling parts utilize a variety of connecting structure to maintain the parts in a coupled condition. Bolts, nut connectors, quick release sleeves and radially movable detents, and bayonet type connectors are all commonly used with fluid couplings. Often, one or both of the fluid coupling parts include an internal valve for controlling fluid flow through the coupling part and some fluid couplings provide automatic valve operators to open or close the coupling part valves in dependency upon the condition and operation of the coupling connectors. Other couplings employ separately operable valve operators wherein the position of the valve is no operated by the connection or disconnection of the coupling parts.
In fluid couplings having high flow capacity and low pressure loss, and wherein valving in such couplings is desired, ball valves are often used because of their quick operation, high flow capacity and low flow restriction characteristics. Normally, ball valve type fluid couplings employ valve operators exteriorly accessible for positioning the valves as desired. Also, with manually operated ball valve couplings it is also known to employ interlock mechanism between the coupling part connectors and the valve operators to prevent the valve parts from being disconnected if one or more of the valves are in an open, or partially open, condition. The assignee's U.S. Pat. No. 4,438,779 discloses a coupling of this type.
Because of the size of the ball valve in ball valve type fluid couplings, heretofore, ball valve couplings have not been available which are of the low-spill type, i.e. minimal loss of fluid occurs as the coupling parts are separated after the valves have been closed. Those known ball valves having interlock structure between the coupling part connectors and the valve operators have not been of the low-spill type and a need exists for fluid couplings which produce minimal fluid loss upon disconnection of the coupling parts and wherein coupling part disconnection can only occur if the valves are fully closed. Environmental requirements dictate such characteristics.